I'm stumped...truck no worky.

[907 Chevy]

Alright guys, I'm completely stumped by this and need some help figuring it out...

I replaced the intake manifold recently on my 1995 K1500 and everything went back together fine, BUT my injectors are not firing and I cannot connect to the PCM nor can I pull codes via the paperclip trick...no idea if these separate issues are related at all.
I swapped out ignition modules since I had an extra module laying around and no luck. I also pulled the dizzy and installed a new AC Delco pickup coil and turned the distributor with a drill while I checked coil output with a multimeter to make sure it was working properly, all good there and still the injectors refused to fire.
I checked both ecm fuses in the underhood fuse block...the fuses are good.
I checked all PCM grounds for continuity...grounds are good.
I jumped the injectors with 12v and the injectors are functioning properly.
I swapped in another PCM and still no luck(this is NOT a known good PCM).
I checked input voltage at the PCM with key on and am getting good voltage to the PCM.
Thinking that maybe my chip got smoked somehow, I burned a brand new chip and...nothing.
I've checked and rechecked that all sensors are properly connected.
Fuel pressure is good and pump primes as it should with key on.

I did swap to a 454 throttle body and rewired the IAC and TPS while I was doing the intake. I just matched wire colors when wiring in the flat TPS connector...did I wire it wrong maybe? I did unplug the TPS connector and tried to fire it just in case that was the issue and still no luck.

Perhaps I should test this TPS for proper function...I'm grasping at straws here though. What did I screw up?? The truck ran before I tore it apart, although I was experiencing a strange high/hanging idle and I think this issue happened before I replaced the intake because the truck wouldn't start the last couple times I tried to fire it up before removing the intake.

Thoughts?

[pmkls1]

What does the CEL do when you turn the ignition on ? Does it come on steady, or flash continuously, or not come on at all ? It sounds like a memcal issue maybe, but that is just a SWAG at this point. The behavior of the CEL sometimes gives a clue to what's going on.

[907 Chevy]

CEL stays solid, no rapid flashing that usually points to a bad PROM. It also stays constantly on instead of flashing when I jump the A and B terminals at the ALDL connector.

[pmkls1]

Well, I don't have much at this point I'm afraid. I would definitely try to focus on communicating with the PCM though. It sounds like for whatever reason the PCM isn't really functioning but the fact that the fuel pump primes is odd. I would suggest checking for power to all of the junctions and fuse blocks aside from the ignition inputs to the PCM. Another question would be does the truck have VATS ?

[907 Chevy]

No, VATS is not enabled in my bin. I thought that if the fuel pump is priming properly then that would point to a functioning PCM, but why can't I pull codes?...very odd indeed. I'm lost. Something got hosed and I can't figure out what it is.

[chevmasta]

Do you have vRef?
(reference voltage....5V to your TPS)